Process of producing artificial fibrous material



Patented Dec. 8, 1942 I ,UNITED STATES PATENT OFFlCE PROCESS OF PRODUCING ARTIFICIAL v FIBROUS MA'IE RIAL Georg Heberlein, Wattwil, Switzerland No Drawing. Application April 4, 1941, Serial No. 386,837. In Germany April 9, 1940 3 Claims.

If direct dyestuffs are used it will-be advantageous to dye before supertwisting, as otherwise it is often difficult to obtain even shades. Asto the election of dyestufis, such dyestuffs may be improvement consists therein that the yarn after untwlsting it, is exposed to a wet heated atmosphere in a loose l. e. untensioned state.

One advantage of my invention in comparison with the before mentioned processes consists therein that it will-be possible by the new process to obtain durable wool effects. Under durable wool effects I understand permanent effects espea used which do not or do only slightly alter. their colour shadeby' a treatment with formaldehyde. In general these are the same dyestuffs recommended by thedyestuff factories for finishing crease-resistant goods.

' It will also be possible to combine the formaldehyde treatment with a finish to render the yarns at the same time water repellent, for instance with stearylor montanyl-isocyanates or octadecyloxymethyl-pyridium. chloride. Generally the wool eflect is developed on exposing the formerly supertwisted steamed and untwisted. yarn loosely to the air; steaming will accelerate the curling of the yarn. In the case that the cially wool effects which resist the mechanical influences during weaving, knitting and further finishing as well as to laundering of the goods, made out of such yarns. I

A further advantage of the material manufactured according to my process is that it does not change its character during the wearing of clothes or theuse of textiles made therefrom.

As another advantage of my process I mention that it renders commercially dyed goods more fast to washing.

Another advantage consists therein that yams produced according to my process andclothes or knitted goods manufactured from these yarns show a reduced tendency to shrink on laundermg.

According to my invention artificial silk preferably produced as described in the above-mentioned patent specifications is treated with formaldehyde or formaldehyde yielding substances and in the presence of acid reacting catalysts at temperatures of preferably 90-160 C.

The process may be applied to any sort of .artificial fibers capable of reacting with formaldehyde, such as artificial fibers of regenerated cellulose. It is useful to treat with formaldehyde following the processes described in the Patents 2,019,185 or 2,019,183, but it is also possible to treat with formaldehyde at an earlier stage or to combine the formaldehydetreatment with the steaming or drying step. If colouredyarns are desired it is suitable todye with naphtoleor vat dyestuffs, for instance before supertwistln and before the formaldehyde treatment is applied.

yarn is to be further treated or used under tension for instance on bobbins to be woven in a pile fabric then the wool effect may be developed advantageously by steaming after the weaving and cutting ofl. It may even be of advantage in such a case to treat with the formaldehyde after weaving. Pile fabrics manufactured accordin to my process are characterised by a full hand, great tightness and uniform appearance.

The formaldehyde treatment corresponds generally to the treatment described in the specification of the copending Frauenfelder continuing application No. 357,119 filed on September 17, 1940, and examples are given below.

As suitable catalysts there are employed strong their at elevated temperatures acid reacting salts;

soluble aluminium salts such as aluminium chloride, aluminium sulphate, aluminium thiocyanate or the like. In addition there may also be employed zinc chloride and ammonium thio- In practice I have used a highly dis-' sociatedacid or a substance yielding such an cyanate.

strictly classified as highly dissociated. but also those which are moderately dissociated i. e. those having a dissociation constant above 3x The formaldehyde is preferably applied to the yarn by impregnating it with a solution of technical formaldehyde. To this impregnating bath the catalysts may be added. After squeezing out and drying the goods are submitted to heating in dry state.

Depending on the material to be worked, the impregnation can be carried out in a cold or hot bath. The duration of 'the impregnation period also is varied according to the kinds of goods employed. The goods may be subjected to 60-90 C. for drying and afterdrying the temperature is elevated at about 90-160 C., but with temperature above about 130 C. great care must be exercised. The duration and temperature of the heating is governed to some extent by the catalyst and kind of material employed. At a low temperature, for instance 100 C. obviously longer treating may be employed, while at higher temperatures a shorter .period of heating is or-.

dinarily employed. The treatment with formaldehyde or its compounds with the catalysts herein described and atthe temperature stated for the period of time given herein causes a reaction between the formaldehyde and cellulose and a compound of cellulose and formaldehyde is formed. The content of chemically bound formaldehyde -in the cellulose may be analyticallytain condition, but if one would try to fix such effects following the methods referred and described in the examples the eafter, the result would be zero. The following are examples of the process and it is to be understood that the examples are purely illustrative and that the invention is not restricted thereto.

Example 1.Viscose artificialI-silk yarn of a size of 450 denier with a twist of 100 per meter is supertwisted to 1200 twists per meter. Thereupon the supertwisted yarn which has been placed on bobbinsis steamed at 2 atmospheres pressure for half an hour. After drying the yarn is untwisted past the zero point and brought to 50 twists per meter in the opposite direction. The resulting yarn is formed into hanks and is woollike. Afterwards the wool-like or curled hanks are impregnatedwith a solution of 200 cc. formaldehyde 40% and 4000. solution of aluminium thiocyanate of 17 B. per liter, squeezed out, predried at 60 C. and heated to 120 C. for 10 minutes, soaped, rinsed and loosely dried.

Example 2.The treatment is the same as in Example 1, but after the untwi'sting of the yarn past the zero point it is steamed in a loose state. Example 3.Copperammonium artificial silk of a size of 120 denier and not twisted is given 2500 twists per meter. Then the yarn spools are steamed for 40 minutes at 4 atmospheres pressure. After drying the yarn is untwisted to the zero point and in this condition is cut into staple fibers on a suitable cutting machine. After twisting of the staple fibers the yarn is treated with formaldehyde as described in Example 1.

Example 4.Delustred copperammonium artificial silk yarn of a size of 150 denier with a twist of 200 per meter issupertwisted to 2000 twists drying the yarn is untwisted on the twisting machine past the zero point and brought. to twists per meter in the opposite direction. Thereafter the yarn is steamed in the form of hanks and afterwards impregnated with a solution of cc. formaldehyde 40% and 3 g. ammoniumchloride per liter, squeezed out, dried at 60 C. and treated to 120 C. for 15 minutes and finished as in Example 1.

Example 5.The impregnation bath of Example 4 is replaced by he following bath:

Formaldehyde 40% cc Technical zinc chloride per liter g -20 the pH of the impregnation bath being brought if necessary to 4. The yarn is impregnated, squeezed out, dried at 00 C. and-heated to C'. for 20 minutes and finished as in Example 1. Example 6.Viscose yarn of a size of 450 denier is supertwisted to 1250 turns per meter, steamed on bobbins at a pressure of 3 atmospheres for 40 minutes, dried and untwisted past the zero point and brought to 60 twists per meter in the opposite direction.

The so treated yarn is then woven into a pile fabric as pile yarn. After cutting the fabric is steamed-without pressure for a sufiicient time to produce the full curliness of the pile. Thereafter the fabric is impregnated on a padding machine with a solution containing per liter Formaldehyde 40% cc 100 Aluminium thiocyanate solution of 17 B cc 40 The excess liquid is squeezed off, the fabric dried on a stenter frame at 60 to 70 C. and then heated to 120 C. for 17 minutes preferably in a loop dryer. Hereafter the fabric is washed, soaped and finished in the usual way.

The fibrous material treated according to the above mentioned examples possesses a lasting curliness which resists repeated laundering and has great softness, the fibers being readily elongatable whensubjected to a stretching force and being sufiiciently elastic to return to or nearly to their original position upon discontinuance of said stretching force and contains a small amount of chemically bound formaldehyde.

I use the term supertwist or supertwisting herein with the same meaning as set forth in the specification of said prior U. S. Patent 2,019,185, commencing in line 47, first column, page 1 thereof, and ending in line 21, secondcolumn.

While the invention has been described in detail according to the preferred manner of carrying out the same, it will be obvious for those skilled in the art that changes and modifications may be made therein without departing from the spirit or scope of-the invention.

What is claimed as new and desired to be secured by Letters Patent is:

, 1. A process for producing a new artificial fibrous .material which comprises supertwisting an artificial silk yarn, setting the twist therein and thereafter untwisting the yarn to produce a wool-like effect, and combining this process with a treatment with formaldehyde or formaldehyde After acting catalysts at temperatures or a,ao4,oeo

to form a formaldehyde-cellulose compound yielding substances in the presence of acid re- 2. Process for producing a new artificial fibrous material which comprises supertwisting an artificial silk yarn, setting the twist therein and thereafter untwisting the yarn to produce a wool efiect, and combining thi process with a treat--- preferably ment of the said material with formaldehyde ora formaldehyde-yielding substance, which treatmentv is as follows: impregnating the material with the formaldehyde or a formaldehyde-yielding substance in the presence of an acid catalyst having a dissociation constant above 3 l0- or a substance yielding such an acid at elevated temperature, removing the excess liquid and subjecting the said material to a temperature of above about 90 C. for a. sufllcient length of time giving greater durability to the wool-like effect.

3. Process for producing a new fibrous material which comprises treating artificial silk fibers to render them wool-like and combining this treatment with a treatment of the said fibers (mom HEBERLEIN. 

